fix: remove unnecessary warnings in select module

Author: ddotta

book/content/data_manipulation/_select_columns.qmd

@@ -53,30 +53,9 @@ iris_dt[1:3,.(Petal.Length,Petal.Width)]
 ```
 :::
 
-**Keep in mind that when:**  
-- Square brackets are used:  
-    - **Selecting only one column** from a `DataFrame`, the output is a `Series`;  
-    - Whereas **if there is more than one column selected**, the output is a `DataFrame`.  
-- `select()` method is used:  
-    - **The output is always a `DataFrame`** rather than a `Series` even if one column is selected.  
-    => If you need a `Series` you can use the `to_series()` method. See [here](#get-series-from-dataFrame).
-
-```{r}
-#| label: select-output-polars
-
-inherits(as_polars_df(iris)[,"Petal.Length"],"Series")
-inherits(as_polars_df(iris)[,"Petal.Length"],"DataFrame")
-inherits(as_polars_df(iris)[,c("Petal.Length","Petal.Width")],"DataFrame")
-inherits(as_polars_df(iris)[,c("Petal.Length","Petal.Width")],"Series")
-```
-
-With Polars if you want to obtain a result in an R data.frame, you can simply use the function `as.data.frame()`. See [here](#from-seriesdataframes-to-vectordata.frames) for examples.
-
-::: {.callout-tip}
-Beyond the minor differences discussed above, there are **two major reasons why you should use the `select()` method over the syntax with square brackets:**  
+There are **two major reasons why you should use the `select()` method over the syntax with square brackets:**  
 - When you select and transform multiple columns with `select()` method, Polars will run these selections **in parallel**;  
 - Expressions used in `select()` method can be optimised in [lazy mode](#introduction-to-lazy-mode) by the query optimizer.
-:::
 
 ### Selecting by data type